Thursday, October 25, 2012

Gulf Stream destabilizing methyl hydrates

The Gulf Stream is an ocean current that modulates climate in the
Northern Hemisphere by transporting warm waters from the Gulf of Mexico
into the North Atlantic and Arctic oceans1, 2.
A changing Gulf Stream has the potential to thaw and convert hundreds
of gigatonnes of frozen methane hydrate trapped below the sea floor into
methane gas, increasing the risk of slope failure and methane release3, 4, 5, 6, 7, 8, 9.
How the Gulf Stream changes with time and what effect these changes
have on methane hydrate stability is unclear. Here, using seismic data
combined with thermal models, we show that recent changes in
intermediate-depth ocean temperature associated with the Gulf Stream are
rapidly destabilizing methane hydrate along a broad swathe of the North
American margin. The area of active hydrate destabilization covers at
least 10,000 square kilometres of the United States eastern margin, and
occurs in a region prone to kilometre-scale slope failures. Previous
hypothetical studies3, 5
postulated that an increase of five degrees Celsius in
intermediate-depth ocean temperatures could release enough methane to
explain extreme global warming events like the Palaeocene–Eocene thermal
maximum (PETM) and trigger widespread ocean acidification7.
Our analysis suggests that changes in Gulf Stream flow or temperature
within the past 5,000 years or so are warming the western North Atlantic
margin by up to eight degrees Celsius and are now triggering the
destabilization of 2.5 gigatonnes of methane hydrate (about 0.2 per cent
of that required to cause the PETM). This destabilization
extends along hundreds of kilometres of the margin and may continue for
centuries. It is unlikely that the western North Atlantic margin is the
only area experiencing changing ocean currents10, 11, 12;
our estimate of 2.5 gigatonnes of destabilizing methane hydrate may
therefore represent only a fraction of the methane hydrate currently
destabilizing globally. The transport from ocean to atmosphere of any
methane released—and thus its impact on climate—remains uncertain.

A number of outlets have picked up on this story, and it's easy to see why. This is another classic we-thought-it-would-take-thousands-of-years moment. In recent years methyl hydrate deposits in the Arctic, and especially the shallow deposits in the East Siberian Arctic Shelf, have grabbed the spotlight. Another recent study made headline when it warned of large methane deposits under Antarctica. It seemed that methane was on the move North and South, and the poles grabbed most of the popular attention. But:

Methane hydrates are over over the place. Including places in the ocean dramatically warmed by shifting ocean currents. So there's that.

Key points from the study include:

1. Methyl hydrate deposits are being destabilized by warming oceans right now.
2. We don't know how much of this carbon will make it into the atmosphere, vs contributing to the acidification of the oceans.
3. The study looked at part of the North American coastline, but this process is likely unfolding in other parts of the world as well.
4. Reports of the death of the clathrate gun hypothesis have been greatly exaggerated. This is only one of many recent studies to illustrate that carbon-cycle feedbacks have the potential to add large amounts of greenhouse gases to the atmosphere. How fast? Not overnight, but not necessarily over thousands of years, either.
5. With vulnerable carbon stores in the Arctic, the Antarctic, and on the continental shelves in between, it is becoming painfully clear that anthropogenic global warming is a game of Russian roulette played with a semiautomatic.

8 comments:

Whilst I've changed my opinion on the loss of Arctic sea ice - I now think we'll see a virtually sea ice free state this decade. I still remain sceptical about the rate of impact of CH4 emissions. My position regarding methane hydrates in the ESS remains that I am sceptical of how much what is being observed there is due to post glacial warming and inundation. The evidence shows that the Arctic has been subject to super-interglacials in the past, and that during the holocene there were warm periods with little sea ice. Yet we haven't seen a methane driven catastrophe. Evidence from the PETM shows that then CH4 emissions spanned tens of millenia, suggesting that the emissions from the ocean will be relatively slow.

This doesn't mean it's not a problem, you're probably aware of recent research showing that land permafrost has the potential to take the warming out of our hands within decades. And it is the land that concerns me more than the ocean deposits. Lawrence et al examine permafrost stability during modelled rapid ice loss events. They show that the warming from RILEs propagates well inland from the Arctic ocean.http://farm9.staticflickr.com/8196/8100729489_ea6686a89e.jpgAnd it does so over the areas of permafrost. The earlier the event and the warmer the permafrost initially is, the more the impact is. Furthermore other research (forget which paper) shows that land permafrost responds rapidly to changes in air temperature.

Given my pessimism about prospect for humans reducing CO2 emissions I actually think we are re-running the PETM. It's just that I don't think the process will be as fast as some people seem to think. I know that current CH4 levels are increasing much faster than the PETM, but the start of the PETM unfolded over some 20k years. So I think talk of catastrophe by 2100 is overstated - what catastrphes there will be will be due to our CO2 emissions from fossil fuel burning and the impacts of peak oil and gas, possibly coal. What a re run of the PETM means is that if we hit a turning point and realise how stupid our current trajectory is, we may desist from CO2 emissions only to see the natural environment take over.

But as I say; I'm pessimistic on this score. I think we'll burn all the fossil fuels we can, the only limitation being economics and extraction technology. That doesn't mean I subscribe to a re run of the End Permian extinction (80% of life wiped out) because I don't think we have enough fossil fuel.

"What a re run of the PETM means is that if we hit a turning point and realise how stupid our current trajectory is, we may desist from CO2 emissions only to see the natural environment take over."

Exactly. And just to sprinkle a little pessimism on your pessimism, here is a related concern; if human civilization reaches a point where, due to our abuse of the climate or for other reasons or a combination of reasons, we cease to become steadily richer and start to get poorer, carbon-cycle feedbacks may be strong enough to sustain warming. This would mean our planet would become steadily less hospitable to human life even as we became less and less able to cope with the changes.

Most excellent blog ... but please stop using methyl hydrate (a bad synonym for methanol) when you mean methane hydrate (or better, methane clathrate since the methane is simply in a cage and not hydrated).

For example:

Methanol is often sold as “methyl hydrate”, implying the incorrect formula CH3OH2, while the correct formula is CH3–OH.Many organic molecules, as with inorganic molecules, form crystals that incorporate water into the crystalline structure without chemical alteration of the organic molecule (water of crystallization). The sugar trehalose, for example, exists in both an anhydrous form (melting point 203 °C) and as a dihydrate (melting point 97 °C). Protein crystals commonly have as much as 50% water content.Inorganic chemistryHydrates are inorganic salts "containing water molecules combined in a definite ratio as an integral part of the crystal"[1] that are either bound to a metal center or that have crystallized with the metal complex. Such hydrates are also said to contain water of crystallization or water of hydration. If the water is heavy water, where the hydrogen involved is the isotope deuterium, thenMethanol - Wikipedia, the free encyclopediaen.wikipedia.org/wiki/MethanolSystematic name. Methanol. Other names. Hydroxymethane. Methyl alcohol. Methyl hydrate. Methyl hydroxide. Methylic alcohol. Methylol. Wood alcohol ...Methanol fuel - Denatured alcohol - Methanol (data page) - Methanol economy

What is methyl hydratewiki.answers.com › Wiki Answers › Categories › Science › ChemistryMethyl Hydrate is simply another word for Methanol; which is the simplest form of alcohol. By that I mean it has the least atoms in each molecule of all the ...

Denatured Alcohol vs Methyl Hydrate [Archive] - Bike Forumswww.bikeforums.net › ... › Bike Forums › Bicycle Mechanics38 posts - 15 authors - Jul 10, 2005However, they did all carry Methyl Hydrate and all said it is the equivalent. ... Would just like to know if the Methyl Hydrate is an acceptable ...

Methyl Hydrate, Glycerine, Plasters - Hyoomik.comwww.hyoomik.com/images/technique1.htmlMethyl Hydrate is available in your local hardware store. It is used as antifreeze, as a fuel for camp stoves, and as a solvent for shellac. It is what keeps shellac in ...

Deposits, hydroxide methane in the oceansIt happens that the methane hydroxide is very unstable; for that reason the deposits in Siberia are bursting suddenly at a certain temperature variation.It was logical that the frozen deposits on land broke out first; because when heated the planet, the temperature rises first on land and much later on the ocean floor. But what happens when hydroxide deposits of methane in the oceans reach the melting point? : Tsunamis.